class Group extends PIXI.Container {
    constructor() {
        super();
        this._defWidth = -1;
        this._defHeight = -1;
    }

    get defWidth() {
        this._defWidth || this.width;
    }

    set defWidth(value) {
        if (value != this._defWidth) {
            this._defWidth = value;
        }
    }

    get defHeight() {
        return this._defHeight || this.height;
    }

    set defHeight(value) {
        if (this._defHeight != value) {
            this._defHeight = value;
        }
    }
}